The game's plot is unrelated to that of its predecessors, which involves Mario and Luigi being shrunken and inhaled into the body of their nemesis,Bowser. The Mario brothers learn to assist Bowser, who is unaware of their presence, as he combats Fawful, who has taken control of the Mushroom Kingdom. The gameplay focuses on the co-operation of the trio, who use their specific abilities to solve puzzles and fight enemies and thus progress through the game. Similar its predecessors, its role-playing style emphasizes a turn-based battle system focused on timing accuracy, and is comedic in nature.

Bowser's Inside Story was first revealed at Nintendo's Tokyo Press Event on October 2, 2008,[1] and its English title and Western release dates were announced at E3 2009.[2] The game was both critically and commercially successful, gaining an aggregate score of 91% from GameRankings[3] and 90 from MetaCritic,[4] and selling 4.13 million copies worldwide as of April 2011.[5]